adduser: add new recipe

This is a utility from debain to add users/groups to the system,
which is actually a perl wrapper of the useradd/groupadd command.

We want this to replace the same commands provided by busybox.

Homepage: https://alioth.debian.org/projects/adduser



Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>